That would depend on Prox Cen b's atmosphere and magnetic field, and we don't know much about either.
At the top of its atmosphere (if it has one at all; otherwise, at the surface) Prox Cen b would get about 500x more EUV/X-Ray radiation in an average day than we get at the top of Earth's atmosphere, so putting Earth into an orbit whose periastron is similar to Prox Cen B's average orbital distance would not be good news for many of Earth's near-surface organisms.
The planet is in such a tight orbit around Prox Cen that it may not have any atmosphere thanks to erosion by the stellar wind. However, it might have a sufficiently strong magnetic field that erosive loss is checked. It also might not be a rocky planet rather than something like a small Neptune, with a deep atmosphere. Finally, Venus's magnetic field is negligible, and Venus is rocky, yet it has a thick atmosphere; Prox Cen b could be like a big Venus, for all we know so far.
At the top of its atmosphere (if it has one at all; otherwise, at the surface) Prox Cen b would get about 500x more EUV/X-Ray radiation in an average day than we get at the top of Earth's atmosphere, so putting Earth into an orbit whose periastron is similar to Prox Cen B's average orbital distance would not be good news for many of Earth's near-surface organisms.
The planet is in such a tight orbit around Prox Cen that it may not have any atmosphere thanks to erosion by the stellar wind. However, it might have a sufficiently strong magnetic field that erosive loss is checked. It also might not be a rocky planet rather than something like a small Neptune, with a deep atmosphere. Finally, Venus's magnetic field is negligible, and Venus is rocky, yet it has a thick atmosphere; Prox Cen b could be like a big Venus, for all we know so far.
Venus is pretty interesting: https://link.springer.com/article/10.1007/s11214-017-0362-8
Maybe someday we'll have similar (well, almost certainly strictly superior) probes around Prox Cen b.